Typescript Error Expected 0 arguments, but got 2 in Ionic Framework

Question

The typescript compiler gives me this error

typescript: src/pages/login/login.ts, line: 33 Expected 0 arguments, but got 2. L32: this.auth.loginAPI(this.registerCredentials) L33: .subscribe(response => {

With this code (2 files):

// auth-provider.ts
public loginAPI(credentials: {email:string,password:string}) {
  return this.http.post(this.apiUrl,data);
}

// login.ts
this.auth.loginAPI(this.registerCredentials)
  .subscribe(response => { 
    console.log(response);
  }, err => {
    console.log(err);
  });

The funny thing is that the code works (I edit any file, my ionic serve reloads and the page renders without any problem).

Any idea?

Environment cli packages: (/usr/local/lib/node_modules)

@ionic/cli-utils  : 1.19.0
ionic (Ionic CLI) : 3.19.0

global packages:

cordova (Cordova CLI) : 7.0.1

local packages:

@ionic/app-scripts : 3.1.5
Cordova Platforms  : ios 4.4.0
Ionic Framework    : ionic-angular 3.9.2

System:

Node  : v8.9.3
npm   : 5.5.1
OS    : macOS High Sierra
Xcode : Xcode 9.2 Build version 9C40b

For clarification, I've tried passing two separate parametrs, a Class, even only one parameter to test it, every time I get the same compiler error. Even SublimeText highlights the error: does it means that we should do it in another way? — ddalcero
– ddalcero, Commented Dec 15, 2017 at 8:37
The problem reported by the compiler is with the .subscribe, not with the credentials passed to loginAPI. I'm editing the question to clarify it better. — ddalcero
– ddalcero, Commented Dec 15, 2017 at 9:21

ddalcero · Accepted Answer · 2017-12-15 09:36:56Z

7

The problem is with the loginAPI function definition. Adding the return type to Observable<any> made the compiler happy and solved the issue.

// auth-provider.ts
public loginAPI(credentials: {email:string,password:string}):Observable<any> {
  return this.http.post(this.apiUrl,data);
}

Still I don't really understand very well why, but at least now it compiles without any error.

answered Dec 15, 2017 at 9:36

ddalcero

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4 Comments

davecar21 Over a year ago

have you find the reason why this is happening?

ddalcero Over a year ago

@davecar21 seems to me that the compiler is forcing the declaration of the return type...

davecar21 Over a year ago

Is there any other way rather than using Observable<any>

ddalcero Over a year ago

@davecar21 depends on the return type of your function. What are you trying to accomplish or solve?

Sajeetharan · Accepted Answer · 2017-12-15 02:11:14Z

1

In order to handler this you can create a class as follows,

public class credentials export {
   email : string;
   password: string;
}

and then,

public loginAPI(inCredentials : credentials ) {
  return this.http.post(this.apiUrl,data);
}

answered Dec 15, 2017 at 2:11

Sajeetharan

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4 Comments

ddalcero Over a year ago

Tried with a Class, with an array, with two separate parameters... Doesn't work, same error every time.

Sajeetharan Over a year ago

what do you mean by with an array ?

ddalcero Over a year ago

I'm calling array the object I pass in my first post ( {email:string,password:string} )

ddalcero Over a year ago

I know, but doesn't work either way. Even with your proposed solution I've got the same error

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